why servo motor in the governor is called as motor though it has no electrical connections

 

What kind of control system are you referring to, and what kind of servo device are you referring to?

The definition of a motor is any device that converts energy of any kind into mechanical energy.

There are servo motors (which convert electrical energy into rotational force). These are also connected to control systems, because many of them are used to precisely position tables or shafts, etc.

A servo converts electrical energy (amps applied to a coil; amp-turns) into torque which is applied to some mechanical element. The mechanical element could be a rotor or a shaft or a spool or a hydraulic jet tube.

 

Kapil... your question was not very specific so my reply will be centered on the definition in IEEE Std 100. It's titled "The IEEE Standard Dictionary of Electrical and Electronic Terms!"

1. Servomechanism:
(A) A feed-back control system in which one of the systems signals represents mechanical motion.

(B) Any feed-back control system.

(C) An automatic feed-back system in which the the contolled variable is mechanical motion, or its time derivatives.

2. Servomotor
An actuating device to position turbine control elements via (I'm now paraphrasing) electrical, pneumatic, hydraulic, linear actuator, or other, means.

Thus, per your observation, since there are no wires, the turbine control elements are probably pneumatic or hyraulically powered!

Regards, Phil Corso